Lignin concentration in wood

Where, ki is the actual reaction rate constant, k2 is the overall rate constant for the change in the diffnsional resistance in the particle, LoUnd L are the lignin concentrations in wood at time 0 and t, respectively. 

When the proper conditions are met, UV microscopy can provide a quantitative measure of the lignin concentration in a microscopic area of wood tissue according to the Beer-Lambert law ... 

Donaldson LA (1987) S3 lignin concentration in radiata pine tracheids Wood Sci Technol 21 227-234... 

Since lignin content In wood Is normally expressed on weight basis, lignin concentration can be more appropriately expressed as ... 

VC Tirumalai, U Agarwal, and JR Obst. Hetereogeneity of Lignin Concentration in Cell-corner Middle Lamella of White Birch. Wood Sci. Tech. 30 99-104, 1996. 

In wooden tubs, the maintenance of a sanitizer residual becomes compHcated due to the leaching of tannins and other organic matter from the wood into the water. The sanitizer demand of these substances must be overcome in order to maintain proper residual concentrations. As the tub ages, the leaching of these materials decreases, but bleaching of the wood may occur as the lignin (qv) in the wood reacts with sanitizers. 

Other spherical fillers include carbon black. This has several roles particularly in combination with elastomers, e.g., black pigment, anti-oxidant and UV stabiliser, reinforcing filler, and an electrical conductor when used at 60% concentration. Wood flour is particularly effective in phenol/formaldehyde and melamine or urea/formaldehyde thermoset resins because the phenolic lignin component in the wood reacts with the methylol groups (-CH2OH) in the growing polymer. 

Recent work has concentrated on the use of ALCELL lignin as a substitute for phenol-formaldehyde resins in wood adhesives, particularly wafer-board. Some of the results obtained when a PF resin (Bakelite 9111) was replaced with different levels of hardwood ALCELL lignin in waferboard manufacture will be briefly discussed below. Table III shows the conditions used for waferboard manufacture. 

Bark can roughly be divided into the following fractions fibers, cork cells, and fine substance including the parenchyma cells. The fiber fraction is chemically similar to that of the wood fibers and consists of cellulose, hemicelluloses, and lignin. The other two fractions contain large amounts of extractives. The walls of the cork cells are impregnated with suberin, whereas the polyphenols are concentrated in the fine fraction. 

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